Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 5, pp. 757−762.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
L.N. Chukhlomina, Yu.M. Maksimov, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 5, pp. 705−710.
INORGANIC SYNTHESIS AND INDUSTRIAL
Relationships in Synthesis of Chromium Nitride
by Combustion of Ferrochrome in Nitrogen
L. N. Chukhlomina
and Yu. M. Maksimov
Department of Structural Macrokinetics, Tomsk Scientiﬁ c Center, Siberian Division,
Russian Academy of Sciences, Tomsk, Russia
Tomsk Polytechnic University, Tomsk, Russia
Received July 15, 2008
Abstract—Nitridation of commercial ferrochrome in the self-propagating high-temperature synthesis mode was
studied. The influence of the key parameters of the process (nitrogen pressure, sample diameter, particle size
distribution of the initial powder) on synthesis and phase composition of the combustion products was elucidated.
The microstructural features of nitrided ferrochrome and chromium nitride were examined by electron microscopy.
Acid enrichment of the synthesis products in a hydrochloric acid solution was studied in relation to the composition
of nitrided ferrochrome. Chromium nitride with the residual iron content of 0.3 wt% was obtained, and its thermal
stability and corrosion resistance were examined.
Chromium nitride is superior to other metal-like
nitrides in corrosion resistance, is characterized by
high reﬂ ection coefﬁ cient, and exhibits enhanced wear
resistance. Chromium nitride serves as alloying addition
in smelting of high-chromium stainless steels . Sintered
chromium nitride is of interest for manufacture of fuel
rods and deposition of oxidation-resistant coatings.
However, its extensive application is limited by the lack
of efﬁ cient commercial production technologies. At the
present time, chromium nitride is prepared by furnace
(Tula) and plasmochemical procedures (Riga), both of
which are highly energy intensive and utilize expensive
An attractive method for preparing chromium
mononitride can be found in self-propagating high-
temperature synthesis (SHS) distinguished by the
use of the heat of the chemical reaction between the
components and an autowave mode of the reaction
propagation. Braverman et al.  showed that combustion
of a chromium powder in gaseous nitrogen is suitable
for preparing chromium nitride, the maximal degree
of chromium nitridation being 0.94. Also, it was
demonstrated  that combustion of ferrochrome in
nitrogen yields chromium nitrides (Cr
N + CrN), but this
requires preheating of the initial alloy to 300°C.
Published data suggest that, in low-energy systems,
SHS does not require additional preheating. This
procedure implies preliminary mechanical activation of
the reactants, which provides for an energy store enabling
SHS [4, 5]. Rabinovich et al.  carried out furnace
nitridation of ferrochrome and found that it is expedient
to crush the initial alloy, and the degree of crushing should
increase with decrease in the nitridation temperature.
Taking into account the above-said, we studied here
synthesis of chromium mononitride by nitridation of
ferrochrome in the SHS mode with a view to developing
a new method for preparing technical-grade CrN and Cr.
Using commercial ferrochrome аs the raw material it will
be possible to prepare inexpensive high-quality material.
Our study was concerned with commercial metallo-
thermic ferrochrome containing, wt%: chromium 78.6;
silicon 0.2; aluminum 0.09; carbon 0.04; phosphorus and
sulfur 0.008; iron (balance). Ferrochrome was crushed in
an MPV high-energy planetary mill under water cooling
at the powder:balls ratio of 1:8. To prevent oxidation of
ferrochrome, mechanical activation was carried out in
benzine. The time of crushing was varied from 5 to